Adjustment and preloading of rolling bearing clearance



The assembly of rolling bearings is a common operation in the assembly and repair work of the fitter, and the adjustment and preloading of the rolling bearing clearance is an important part of the rolling bearing assembly work. Accurately grasping the process concept of clearance adjustment and pre-tightening, and correctly applying this process in assembly work is the guarantee of the quality of bearing assembly work.
The clearance of the rolling bearing refers to the maximum amount of movement of the other ferrule in the radial or axial direction when one ferrule is fixed, so the clearance is divided into radial clearance and axial clearance.
When the rolling bearing is assembled, its play should not be too large or too small. If the clearance is too large, the number of rolling bodies that can bear the load at the same time is reduced, so that the load of the single rolling body is increased, thereby reducing the rotation precision of the bearing and reducing the service life; if the clearance is too small, the frictional force is increased, resulting in an increase The increased heat, which exacerbates wear and tear, also reduces the service life of the bearing. Therefore, many bearings must be tightly controlled and adjusted during assembly.
The pre-tightening is that when the bearing is assembled, an axial force is applied to the inner ring or the outer ring of the bearing to eliminate the bearing play and cause initial deformation of the rolling element in contact with the inner and outer rings. Preloading can improve the stiffness and rotation accuracy of the bearing under working conditions. For bearings with large load and high rotational accuracy, most of them work without clearance or even a small amount of interference. In this case, the bearings need to be pre-tensioned during assembly.
The adjustment and preloading of the clearance are usually carried out by means of a suitable axial relative displacement of the inner ring of the bearing to the outer ring.
It is not difficult to see from the above concept of the technology that the adjustment of the rolling bearing clearance can improve the bearing capacity and rotation accuracy of the bearing and improve the service life of the bearing. At the same time, the bearing friction will be intensified and the heat generation will increase. Therefore, it is necessary to ensure good lubrication and heat dissipation while adjusting the clearance or pre-tightening. If improperly adjusted or poorly lubricated, it will in turn increase bearing wear and reduce life. Therefore, the following problems must be noted in the correct adjustment and preloading of the rolling bearing clearance.
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NSK cylindrical roller bearing common fault



The fault phenomenon of NSK cylindrical roller bearings generally shows two types. One is that the temperature of the bearing installation part is too high, and the other is that there is noise in the bearing operation.
1. Bearing temperature is too high
When the mechanism is running, the part where the bearing is installed is allowed to have a certain temperature. When the body of the mechanism is touched by hand, it should be normal to not feel hot, otherwise the bearing temperature is too high.
The reasons for the bearing temperature being too high are: the quality of the lubricating oil does not meet the requirements or deteriorates, the viscosity of the lubricating oil is too high; the assembly of the mechanism is too tight (the gap is insufficient); the bearing assembly is too tight; the bearing race rotates on the shaft or inside the casing; Large; bearing cage or rolling body fragmentation.
2. Bearing noise
NSK cylindrical roller bearings allow a slight running noise during operation. If the sound is too loud or there is abnormal noise or impact, the bearing is faulty.
The cause of noise generated by NSK cylindrical roller bearings is more complicated. One is the wear of the inner and outer rings of the bearing. Due to this wear, the bearing and the housing, the bearing and the shaft are broken, resulting in the axis deviating from the correct position and generating an abnormal sound when the shaft is moving at a high speed. When the bearing is fatigued, the surface metal peeling off will also increase the radial clearance of the bearing to produce abnormal noise. In addition, insufficient bearing lubrication, dry friction, and bearing crushing can produce abnormal sounds. After the bearing wears loose, the cage is loose and damaged, and abnormal noise is also generated.
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